It COULD be either of the issues below, or another common problem is the fuel level sensor. Wiring issues are not common but not unheard of either. If this only happens in Park or Neutral, the gauge signal is not buffered in those ranges and the gauge will bounce around more if the vehicle is rocked back and forth. In all other ranges, the level signal is buffered to reduce gauge fluctuation. Was something done recently to the fuel tank? A little more info like recent repairs would be nice.
09-06-04-007A: Fuel Gauge Does Not Read Correctly, Fuel Gauge Stuck, Check Engine Light,
DTC P0455, P0461 Set (Reposition Fuel Vapor Line) - (Apr 6, 2009)
Subject: Fuel Gauge Does Not Read Correctly, Fuel Gauge Stuck, Check Engine Light On, DTC P0455, P0461 Set (Reposition Fuel Vapor Line)
Models: 2004-2007 Chevrolet Malibu/Maxx
2008 Chevrolet Malibu (Classic)
2008-2009 Chevrolet Malibu
2005-2009 Pontiac G6
2007-2009 Saturn AURA
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This bulletin is being revised to add DTC P0455 and update the Subject and Condition. Please discard Corporate Bulletin Number 09-06-04-007 (06 - Engine- Engine Controls).
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Condition
Some customers may comment on the following conditions:
• The fuel gauge does not rise above the 3/4 mark after a fill up or the fuel gauge appears "stuck".
• An illumination of the check engine light.
• On rare occasions, the fuel gauge does not read the correct level which may result in a no start condition due to a low fuel level.
Upon further investigation, the technician may find DTC P0455/P0461 Fuel Level Sensor Circuit Performance stored in the ECM/PCM
Cause
This condition may be caused by a fuel vapor vent line (that is internal to the fuel tank) interfering with the travel of the fuel level sensor float arm.
Correction
Verify the customer concern.
Remove the fuel tank. Refer to Fuel Tank Replacement in SI.
Disconnect the fuel pressure sensor and sender electrical connections.
Disconnect the evaporative emission (EVAP) vapor line quick connect fittings (1, 2).
Disengage the fuel feed line from the retaining features built into the fuel tank.
Using the J 45722 tool and a long breaker-bar, unlock the fuel sender lock ring.
Remove the sender unit and check for possible interference between the internal vent tube and the sender float arm.
Take the sender vent line and turn it around to the side of the fuel tank sender. Make sure to rotate the vapor line to the spring guide bar.
Important: Cut off ANY excess tie strap. Make sure material doesn't fall into the fuel tank.
Add tie strap, GM P/N 12337820 (note that this is a fuel compatible material), to prevent the vapor line from rotating forward and allowing the pipe to interfere with the fuel level float.
Install an O-ring seal, GM P/N 22682111, onto the fuel sender.
Install the fuel sender assembly into the fuel tank.
Using the J 45722, install the fuel sender lock ring. Turn the fuel sender lock ring in a clockwise direction.
Turn the lock ring until the ring seats on the second detent.
Engage the fuel feed line to the retaining features built into the fuel tank.
Connect the EVAP vapor line quick connect fittings. Refer to Plastic Collar Quick Connect Fitting Service in SI.
Connect the fuel pressure sensor and sender electrical connections.
Install the fuel tank. Refer to Fuel Tank Replacement in SI.
Parts Information
Part Number
Description
Qty
22682111
SEAL, FUEL SDR (O-RING)
1
12337820
TIE STRAP
1
#06-08-49-008A: Erratic Fuel Gauge (Does Not Go To Full or Moves Off Full Too Quickly) (Reprogram PCM) - (Apr 12, 2006)
Subject: Erratic Fuel Gauge (Does Not Go To Full or Moves Off Full Too Quickly) (Reprogram PCM)
Models: 2006 Chevrolet Malibu Maxx
2006 Pontiac G6
with 3.5L Engine (VIN 8 -- RPO LX9)
Built Prior to January 12, 2006
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This bulletin is being revised to update the labor operation code. Please discard Corporate Bulletin Number 06-08-49-008 (Section 08 -- Body & Accessories).
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Condition
Some customers may comment that the fuel gauge is erratic (does not go to Full or moves off Full too quickly).
Cause
This condition may be caused by the Powertrain Control Module (PCM) calibration.
Correction
Important: The Exhaust Gas Recirculation (EGR) valve may need to be updated before reprogramming the PCM. Refer to Corporate Bulletin Number 06-06-04-002A to determine which type of EGR valve is on the vehicle being serviced.
Technicians are to reprogram the PCM with an updated calibration using one of the following procedures:
• On 2006 model year vehicles built with the 3.5L (LX9) engine and a Delphi EGR valve, replace the original Delphi EGR valve with the new Siemens EGR valve kit (P/N 89018175). Install the new Siemens EGR valve, tube and harness connector. Refer to Corporate Bulletin Number 06-06-04-002A and then reprogram the PCM using the updated calibration.
• On 2006 model year vehicles built with the 3.5L (LX9) engine and a Siemens EGR valve, do not replace the EGR valve - just reprogram the PCM using the updated calibration.
Refer to the Engine Control Module Programming and Setup (3.5 or 3.9) procedure in SI for more information.